Goldleaf Hi-vacuum, air-free adapter has many uses. Commonly used as a vent valve for air or inert gas into vacuum systems. Can be used to pull vacuum and close or control flow into or out of the system. Can also be used for sealing standard single neck round bottom flasks to be used as storage vessels. Sampling can be accomplished by removing the teflon plug plug while maintaining inert gas stream through the sidearm. Teflon valve with viton oring provides Hi-vacuum seal and flow control.